I am getting this error while reading a student object from database.
org.springframework.beans.BeanInstantiationException: Failed to instantiate [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.<init>() org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:107)
Full stack trace:
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.<init>() org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857) javax.servlet.http.HttpServlet.service(HttpServlet.java:617) org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) root cause org.springframework.beans.BeanInstantiationException: Failed to instantiate [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.<init>() org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:107) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:775) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:368) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:172) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:446) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:434) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857) javax.servlet.http.HttpServlet.service(HttpServlet.java:617) org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) root cause java.lang.NoSuchMethodException: java.lang.Long.<init>() java.lang.Class.getConstructor0(Class.java:3082) java.lang.Class.getDeclaredConstructor(Class.java:2178) org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:104) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:775) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:368) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:172) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:446) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:434) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857) javax.servlet.http.HttpServlet.service(HttpServlet.java:617) org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
File Student.java
@Entity @Table(name="Student") public class Student implements Serializable{ private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy=GenerationType.AUTO) @Column(name="studentId") Long studentId; @Column(name="studentName") String studentName;
File Controller.java
@RequestMapping(value = "/read.html") public String readStudent(Model model, @ModelAttribute("studentId") Long studentId) { Student student = null; studentId = 2l; try{ student = serviceFile.readStudent(studentId); }catch(Exception e){ model.addAttribute("message", "Some thing went wrong !!!! Exception occoured"); return "message"; } model.addAttribute("student", student); return "read"; }
File daoImpl.java
@Repository @Transactional public class DaoImplFile implements DaoFile { private EntityManager entityManager; public EntityManager getEntityManager() { return entityManager; } @PersistenceContext public void setEntityManager(EntityManager entityManager) { this.entityManager = entityManager; } @Override public Student read(Long studentId) throws NullPointerException { Student student = entityManager.find(Student.class, studentId); if (student!=null) { return student; } else { return null; } }
Answer
The @ModelAttribute("studentId") Long studentId
is the source of the problem, because Spring doesn’t find a method that can provide this Long
object, so it tries to instantiate one and pass it as a method argument. To solve this problem you can either:
Delete @ModelAttribue from the method argument
@RequestMapping(value = "/read.html") public String readStudent(Model model,Long studentId) { Student student = null; studentId = 2l; try { student = serviceFile.readStudent(studentId); } catch(Exception e){ model.addAttribute("message", "Some thing went wrong !!!! Exception occured"); return "message"; } model.addAttribute("student", student); return "read"; }
Create a method that will provide that
Long
Object in your controller@ModelAttribute public void provideStudentId(Model model){ model.addAttribute("studentId", new Long(1)); }
Official Doc
@RequestMapping(path = "/owners/{ownerId}/pets/{petId}/edit", method = RequestMethod.POST) public String processSubmit(@ModelAttribute Pet pet) { }
Given the above example where can the Pet instance come from? There are several options:
- It may already be in the model due to use of @SessionAttributes — see the section called “Using @SessionAttributes to store model attributes in the HTTP session between requests”.
- It may already be in the model due to an @ModelAttribute method in the same controller — as explained in the previous section.
- It may be retrieved based on a URI template variable and type converter (explained in more detail below).
- It may be instantiated using its default constructor.
If the studentId was the parameter name sent from the UI, you can use @RequestParam
like this
@RequestMapping(value = "/read.html") public String readStudent(Model model, @RequestParam("studentId") Long studentId) { Student student = null; studentId = 2l; try { student = serviceFile.readStudent(studentId); } catch(Exception e) { model.addAttribute("message", "Some thing went wrong !!!! Exception occoured"); return "message"; } model.addAttribute("student", student); return "read"; }